The initiation of access by a wireless communication device of a target base station of a cellular communication network can arise under at least a couple of different circumstances. At least a couple of examples of circumstances under which initiation of access occurs include instances in which a wireless communication device is powering up after having been initially switched on from an off condition, a wireless communication device is initiating a call to another wireless communication device, and/or the wireless communication device is transitioning from one location, such as a cell, supported by a first base station to another location, supported by a different base station. In at least some instances, the initial communication with the network infrastructure (i.e. cellular base station), is facilitated through the use of a temporary resource request identifier, which is used to temporarily distinguish one wireless communication device from another wireless communication device, until the wireless communication device is identified, and correspondingly communication resources are allocated and/or are assigned to the wireless communication device by the cellular wireless communication infrastructure for accessing a target base station.
In some instances, the wireless communication device will be in the middle of a call, when a need to obtain communication resources from a new target base station is identified. In such an instance, a wireless communication device may be transitioning away from one cell and toward another cell. In turn, the communication connection with a base station supporting the communication connection in the first cell may become more difficult to maintain, where the wireless communication device's current position may better support continued communication through another (i.e. target) base station that supports communication in another cell. Depending upon the rate at which a wireless communication device may be moving away from the first cell, and correspondingly the rate at which the current communication connection through the first cell is degenerating, there may be a time critical aspect for processing a handoff of the current call connection from a first base station in a first cell to a target base station in another cell, and for correspondingly processing a request for resources from the target base station for supporting continued communication of the already established call connection.
There are generally a finite number of temporary identifiers, that are used to support the various types of request for resources, that are associated with any particular target base station from which resources can be requested, which must support potentially multiple simultaneous and/or nearly simultaneous requests from multiple wireless communication devices. At least one example of a temporary resource request identifier, which serves to temporarily identify a particular wireless communication device relative to a target base station includes a random access channel (RACH) preamble, which is used to request access in at least some cellular wireless communication systems.
In some instances, a subset of the available temporary resource request identifiers may be set aside for at least some of the different types of circumstances under which a resource request might be made of a target base station. For example, at least some of the temporary resource request identifiers may be reserved for facilitating a handover of an on-going and/or an already established call from a source base station to a target base station. In some instances, a particular temporary resource request identifier will be assigned to the wireless communication device. In other instances, the particular temporary resource request identifier that is used might be randomly selected by the wireless communication device from a corresponding list of temporary resource request identifiers associated with the particular type of request.
When multiple wireless communication devices attempt to simultaneously make use of the same temporary resource request identifier, there can sometimes be a conflict, which can preclude one or more of the wireless communication devices, which are attempting to use the same temporary resource request identifier, from being able to successfully complete the request for resources. This can be particularly problematic when the need for obtaining communication resources with a particular target base station might be time critical, such as when requesting a handover during an existing call connection when the existing communication connection via a source base station, which supports the call, is about to fall below the threshold necessary for maintaining the call connection. When one or more wireless communication devices are unable to successfully complete the request for resources in any particular time period, it is generally necessary for a subsequent request to be attempted.
When the particular temporary resource request identifier to be used to access a particular target base station is selected (randomly, arbitrarily and/or following a particular predefined pattern, etc.) by the wireless communication device, there is always the possibility that more than one wireless communication device will independently select the same temporary resource request identifier to be used. The likelihood of the same temporary resource request identifier being selected for use is generally dependent upon the number of wireless communication devices making a selection and the number of available temporary resource request identifiers to select between.
As noted above, the particular temporary resource request identifier used by a particular wireless communication device could be assigned. When the temporary resource request identifier to be used by the wireless communication device is assigned, as opposed to being randomly selected, the likelihood of a conflict can be more closely managed, at least between the particular temporary resource request identifiers that are assigned by the same entity. However sometimes the particular wireless communication devices, which are attempting to request resources from a particular target base station might originate from multiple different source base station which border the area associated with the target base station from a different direction. In such an instance, the common entity which might be able to assign a temporary resource request identifier for all possible wireless communication devices coming from different surrounding source base stations might be several communication steps removed. In such an instance, the latency associated with making the request for a temporary resource request identifier, receiving an assigned temporary resource request identifier, and making use of the same, might preclude the same temporary resource request identifier from being further assigned for some duration, such as, until the same previously assigned identifier is detected as having been used or a corresponding time out period has elapsed, which in turn might limit the rate at which assignment requests using a finite number of temporary resource request identifiers can be supported. In some instances, reserving a temporary resource request identifier for a particular planned request for the entire period of time necessary to communicate the assigned identifier until the time that the assigned identifier is used may be impractical.
Correspondingly, a method which provides for a more effectively assignment and/or selection criteria for allocating one of a plurality of temporary resource request identifiers for use by a wireless communication device in accessing a target base station would be beneficial.